On the relative roles of elevated heating and surface temperature
gradients in driving anomalous surface winds over tropical oceans


Elevated heating by cumulus convection, and sea surface temperature gradients, are both thought to contribute towards surface winds over tropical oceans. We examine relative strength and role of each mechanism by imposing forcing derived from data on a linear primitive equation model with idealized parameterizations for the two forcings, and comparing the response with observed surface winds. Two test cases are studied: one related to the El Niņo-Southern Oscillation, and the other related to the 'dipole' mode in the tropical Atlantic. We find that in both cases, elevated heating dominates the surface zonal wind response, and contributes significantly to the meridional wind response, especially in the subtropics and the South Pacific and South Atlantic Convergence Zone regions. Surface temperature gradients dominate the meridional wind forcing in regions near the equator with strong meridional temperature gradients.

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